President-elect Barack Obama will face his first 100 days with extreme national - and global - scrutiny. The economic crisis is clearly at the forefront of Americans' minds and was a determining factor in this election. What surfaced - from the housing to the credit crises - are the consequences of years of living beyond our financial means. But largely ignored during the campaign was the fact that for years we have also been living beyond our ecological means. There is a pressing need to build an economy that can deliver prosperity for Americans in the face of growing resource constraints.

It is encouraging that Obama pointed to our "planet in peril" during his speech at Grant Park. Obama also must recognize that sustainability is at the core of any long-term financial recovery.

Quite simply, materials on which the economy relies comes from natural resources. In 1997, University of Vermont professor Bob Costanza placed a price tag on the free services nature provides to the global economy: $33 trillion, nearly twice the $18 trillion global GNP at the time.

Globally, humanity's demand on nature for the past two decades has exceeded what the Earth can renew. According to new data just released by our organization, Global Footprint Network, it now takes the planet almost a year and four months to regenerate the resources humans use in one year. The impacts of this debt may not be as obvious as they are on Wall Street, but alarming consequences such as climate change, collapsing fisheries, soil depletion, air pollution and water shortages are already affecting the economy.

In the land of plenty, it is difficult to imagine running an ecological deficit. Yet since 1970, that is exactly what we have been doing. Part of this deficit stems from putting polluting carbon into the atmosphere faster than it can be reabsorbed by forests and oceans, and part from depleting our own ecosystems. The remainder is a result of importing significant amounts of resources from elsewhere in the world.

The United States has maintained its position as a global financial leader, but we are at a crossroads. If we are to continue in this role and remain competitive, we must look to balancing our ecological budget, as other countries have already begun to do. Creating resource-efficient cities, buildings and infrastructure, and fostering best-practice green technology and innovation are all pivotal ways to start. Not only would these efforts benefit our environment, they would create much-needed jobs and help those who are disproportionately affected by the ecological deficit: low-income families, who cannot afford the higher cost of living triggered by resource scarcity, as we've seen in climbing food prices.

In the ecological scenario, there is no bailout. If neglected, ecological debt will make financial crises such as the current one more common, and more intractable.

There are no easy answers when it comes to living within our limits, financially or ecologically. What is clear, however, is that one cannot be solved without considering the other.

Our new president will have 100 days - and the next four years - to prove he can rise to that challenge.